Class NQueensSolver

java.lang.Object

NQueensSolver

public class NQueensSolver
extends java.lang.Object

NQueensSolver - a depth-first search solver of the n queens problem that counts all solutions given n. A non-attacking placement of queens is one in which no pair of queens shares the same row, same column, or same diagonal as another queen.

Field Summary

Fields

Modifier and Type	Field and Description
boolean	verbose boolean verbose - whether or not to print each solution found

Constructor Summary

Constructors

Constructor and Description
NQueensSolver(int n) Construct a solver for finding and counting all solutions to the n queens problem.

Method Summary

Modifier and Type	Method and Description
static void	main(java.lang.String[] args) Obtain the problem size n from args or, if not given, from the standard input.
long	solve() Return the number of solutions to the n queens problem.
long	solveNThreads() Return the number of solutions to the n queens problem, computed with n threads.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

verbose

public boolean verbose

boolean verbose - whether or not to print each solution found

Constructor Detail

NQueensSolver

public NQueensSolver(int n)

Construct a solver for finding and counting all solutions to the n queens problem.

Parameters:

n - the number of queens to place in a non-mutually attacking configuration on an n-by-n board

Method Detail

solve

public long solve()

Return the number of solutions to the n queens problem.

Returns:

the number of solutions to the n queens problem

solveNThreads

public long solveNThreads()

Return the number of solutions to the n queens problem, computed with n threads. Thread number i will count the number of solutions with the row 0 queen placed in column i. The results of all n threads will then be accumulated to a total sum that is returned.

Returns:

the number of solutions to the n queens problem

main

public static void main(java.lang.String[] args)

Obtain the problem size n from args or, if not given, from the standard input. Then find and count all solutions and print the count.

Parameters:

args - optionally, a String array containing a String of a single positive integer n specifying the problem size.